A boat can travel 60km downstream in 4 hours. If the speed of the boat in still water is 13 km/h, then in what time will it cover 30 km upstream?

Given:

Distance downstream = 60 km

Time taken downstream = 4 hours

Speed of the boat in still water = 13 km/h

Distance to cover upstream = 30 km

Formula Used:

Speed downstream = Distance downstream / Time downstream

Speed downstream = Speed of boat in still water + Speed of stream

Speed upstream = Speed of boat in still water - Speed of stream

Time upstream = Distance upstream / Speed upstream

Calculation:

Speed downstream = 60 km / 4 h

Speed downstream = 15 km/h

Speed downstream = Speed of boat in still water + Speed of stream

15 km/h = 13 km/h + Speed of stream

Speed of stream = 15 km/h - 13 km/h

Speed of stream = 2 km/h

Speed upstream = Speed of boat in still water - Speed of stream

Speed upstream = 13 km/h - 2 km/h

Speed upstream = 11 km/h

Time upstream = Distance upstream / Speed upstream

Time upstream = 30 km / 11 km/h

Time upstream = \(\frac{30}{11}\) hours

Time upstream = \(2 \frac{8}{11}\) hours

The correct answer is option 4.